These are accumulations of preganglionic parasympathetic neurons located in the lateral horns of the gray spinal cord in segments S2, S3, S4 (sacral segments 2,3,4). The preganglionic nerve fibers leave the spinal cord via the corresponding front roots, run a short distance at the beginning of the corresponding spinal nerves and then find their way into the complicated pelvic braid (hypogastricus plexus). Here, the preganglionic parasympathetic bundles of threads are called the erection nerves (nn. erigentes or nn. splanchnici pelvici). The name comes from the fact that some of these nerve fibers have a vasodilator effect with respect to the cavernous body tissue in the penis and clitoris.
The connected postganglionic cell bodies are strewn in the hypogastricus plexus and usually immediately adjacent to the organ to be supplied.